1. Field of the Invention
The present invention relates to the reduction of fouling of hydrocarbon oil processing equipment. More particularly, the invention relates to an antifoulant additive composition, a hydrocarbon oil composition containing an antifoulant additive or combinations of additives and a method for using the additives for reducing fouling in oil processing equipment.
2. Description of the Prior Art
In processing various hydrocarbon oils, such as crude petroleum, shale oils, syncrude oils, oils from bituminous sands, and fractions thereof, including naphthas, middle distillate oils, gas oils, heavy vacuum gas oils, topped crudes, atmospheric or vacuum residual fractions, viscous pitches, and the like, or petrochemicals prepared from such oils, it is usually necessary to heat the hydrocarbon oil to an elevated temperature by contacting it with a heated metal surface, e.g., by flowing it through a heating device such as a tube and shell heat exchanger or through the tubes of a direct-fired heater. Many hydrocarbon oils, however, tend to foul metal surfaces with which they come in contact at elevated temperatures by depositing thereon solid or semi-solid materials, commonly called foulants, such as inorganic salts, oxides, coke, tars, polymers, and other carbonaceous matter. Such fouling materially reduces the efficiency of heat transfer from the metal surface to the oil, thereby increasing the amount of fuel required to heat the oil to the desired temperature. It also reduces the hydraulic capacity of the heat exchange equipment (thereby increasing the amount of energy required to pass the oil through the equipment) and in aggravated cases may render it impossible to maintain the desired flow rate. Consequently, hydrocarbon oil processing units must be periodically shut down and deposits removed or the units replaced. Such fouling of heat exchangers, and also equipment such as furnaces, pipes, reboilers, condensers, compressors, auxiliary equipment, and the like, is costly due to the loss of production time and the man-hours required for disassembly, cleaning and reassembly of unit process equipment components. The equipment is usually fabricated of carbon steel, stainless steel, chrome-steels, steel alloys, aluminum or other metallic materials.
A variety of materials has thus far been added to hydrocarbon oils to produce compositions that reduce fouling of heated surfaces and consequently increase heat transfer efficiency. Unfortunately, none of the materials thus far developed is successful in completely eliminating fouling-related difficulties in hydrocarbon processing operations. Consequently, efforts are continuing to effect even greater improvement in such operations to minimize, or preferably completely eliminate, fouling of heated surfaces.
It is, therefore, an object of this invention to provide a hydrocarbon oil composition that has a reduced tendency for fouling.
It is also an object of this invention to provide a method for preparing a hydrocarbon oil composition that has a reduced tendency for fouling.
Another object in this invention is to provide a hydrocarbon oil composition containing an additive that reduces the energy requirements of hydrocarbon processing equipment.
Yet another object is to provide a method for increasing the heat transfer efficiency in hydrocarbon processing equipment.
Still another object is to reduce the energy requirements for heated surfaces in contact with a hydrocarbon oil composition containing an additive or combination of additives.
These and other objects and advantages of the invention will become apparent from the following description.